The advance of photography : its history and modern applications (1911)

154 THE ADVANCE OF PHOTOGRAPHY withstanding their small form, the pictures of these instruments make a clearer and more intelligible impression than single pictures of the same object in a larger form. A single picture of a machine, or of complicated architecture (for example, the choir of the Cologne Cathedral), is often a hopeless maze of details. But in the stereoscope the confused masses are directly denned ; they become distinct in perspective, and the eye perceives with great clearness the interior structure. In this respect the stereoscopic pictures are of equal value to the magic lantern in imparting instruction. Very much more elaborate forms of stereoscope have come into use during the last few years, and it is no uncommon thing for arrangements to be made for two hundred views, on paper or glass, to be examined in succession, the change from one view to the next being made by simply turning a milled head which projects from one side of the apparatus. Enlarging Cameras. — The small photographs obtained by means of the hand camera can be enlarged to any desired size, and the apparatus required for this can be arranged so that the work can be carried out either by the aid of daylight or by artificial light. If the degree to which it is desired to extend the enlargement is relatively small, then there is a great deal to recommend the da}Tlight enlarger. The simplest of this class are usually of a fixed focus type and are made for one degree of enlargement only, but some of the daylight enlargers are so arranged that they can be easily set for enlarging J plate photographs into any ordinary size up to 12 by 10. Again, some enlargers of this type are also capable of being used for the purpose of enlarging other sizes {e.g. \ plates as well as J plates). It is not the usual practice to try to obtain enlarged negatives by this means, although, of course, this can be